动力总成悬置系统刚体模态参数的试验与计算

为研究动力总成悬置系统的动力特性,为悬置元件的设计和优化提供依据,进行了悬置系统怠速工况的运行模态测试和理论计算.首先测试了悬置元件的动刚度、静刚度、阻尼等参数,建立了Matlab计算模型,进行刚体模态计算.结果表明,怠速工况下采用悬置元件动刚度的计算结果与运行模态结果吻合,动力总成悬置系统的刚体模态参数不适宜在实验室环境下测试.     

基于声腔模态分析的汽车低频噪声优化

根据汽车白车身结构有限元模型建立车身声固耦合模型。基于声学模态分析理论,进而求解声腔模态。通过实车怠速噪声和车身悬置激励力测试车内响应点的声压值,进一步验证声固耦合模型。通过峰值频率下的板块单元贡献量和模态应变能优化分析,汽车车内低频噪声降低,有利于提升汽车的NVH性能。     

汽车发动机的隔振研究

汽车振动是影响舒适性的主要因素之一,如何采用有效的技术手段测量分析汽车的振动,日益受到人们重视。采用LMS多分析系统,测试分析发动机振动随发动机转速变化的关系。结果发现,发动机二阶振动是引起车内噪声的主要原因。通过测试悬置系统隔振性能,为进一步提高系统隔振性能提供依据。     

基于自适应Moore响度算法研究高速列车车内声品质（英文）

目的:高速列车的车内噪声以中低频为主,传统的线性和A计权声压级都无法客观描述人耳的听觉感受。本文旨在探索Moore响度应用于车内声品质分析的可行性。创新点:1.提出了一种自适应Moore响度算法(AMLA),该算法可有效提升计算的精度和效率;2.采用AMLA分析了高速列车车内噪声在不同工况下的声品质特征。方法:1.基于信号的等矩形带宽(ERB)谱,提出AMLA方法的理论;2.参照ANSI标准中的仿真信号,评价AMLA的计算精度和效率;3.采用AMLA辨别有色噪声信号与车内噪声样本,验证声品质分析的有效性;4.结合在线搭载试验,运用AMLA分析稳态工况(不同行车速度和空间位置等)和瞬态工况(加速和减速等)下的车内声品质特征。结论:1.相比传统方法,AMLA方法的计算精度和效率相对较高,且适用范围更广;2.高速列车的车内噪声与深红噪声信号具有相似的特征响度分布;3.稳态工况下,车内噪声的响度成分集中在27.6 erbr以内,在300~350 km/h的速度区间内车内声品质较稳定,空间分布特征为"端部大、中间小";4.瞬态工况下,车内噪声在20~27 erbr内的响度成分与列车速度密切相关,而在12~15 erbr内的成分相对稳定。     

不同运行条件下的高速列车车内噪声特性分析（英文）

目的:研究高速列车在不同速度(260~385 km/h)、无砟和有砟轨道以及明线和隧道运行时的车内噪声特性,为高速列车车内减振降噪和车体低噪声设计提供科学依据。创新点:系统分析高速列车在不同运行条件下的车内噪声总值变化、空间分布、频谱特性和声源贡献,掌握车内噪声随列车运行速度的变化规律、轨道型式和隧道混响对车内噪声的影响,研究轮轨噪声、气动噪声和弓网噪声对车内噪声的作用。方法:1.根据不同的列车运行速度,分析车内噪声的变化规律;通过进一步对比头尾车运行时,不同测点位置的噪声总值、显著频率和声源贡献,研究气动作用对车内噪声的影响。2.针对不同轨道型式,分析车内噪声的差异特性;通过进一步对比不同速度下的前、后转向架上方车内噪声测点(其中一个还位于受电弓下方)的噪声总值、显著频率和声源贡献,研究有砟和无砟轨道、弓网噪声对车内噪声的影响以及速度因素的作用。3.对于隧道运行,分析不同速度下在明线和隧道运行时的车内噪声总值和显著频率,研究隧道混响对车内噪声的影响以及速度因素的作用。结论:1.TC01车无论作为头车或尾车运行,车内观光区的噪声均主要受气动作用影响。2.随着列车运行速度的提高,轨道型式的不同对车内噪声的影响有所降低。3.隧道混响对中间车的影响要高于头车。     

声强测量法在摩托车噪声源识别中的应用研究

在摩托车的噪声控制研究中,运用声强测量法对整车左、右侧面在怠速、中速、高速三种工况下的噪声进行了声源识别和研究,通过对声强云图和频谱进行对比分析,确定了排气消声器是主要噪声源,并找到了对噪声量贡献大的主要频段,为下一步采取降噪措施、优化消声器指明了方向,提供了理论依据.     

高速列车车轮多边形对车内噪声的影响

研究目的：研究高速列车车轮多边形特征对轮轨噪声和车内噪声的影响规律,讨论目前国内高速列车车轮镟修指标的不足,为高速列车车轮镟修方法的优化改进提供科学依据。创新要点：系统分析高速列车车轮多边形阶次、幅值和相位等参数对车内噪声的影响规律;提出车轮镟修中仅考虑车轮径跳作为限值是不够的。研究方法：1．基于线路试验,初步分析高速列车车轮多边形状态对车内噪声的影响,进而对车轮多边形特征进行剖析;2．基于带通滤波和快速傅里叶变换,使用MATLAB程序生成不同阶次、幅值和相位的车轮多边形粗糙度数据;3．基于TWINS轮轨噪声原理,使用HWTNS预测含有不同车轮多边形特性的轮轨噪声;4．基于混合有限元-统计能量分析（FE—SEA）方法,建立高速列车客室端部车内噪声预测模型,预测车内噪声;5．通过分析车轮多边形参数、车轮径跳和车内噪声之间的相互关系,研究目前的高速列车车轮镟修指标是否合适。重要结论：1．高速列车车轮径跳值相同,但车轮多边形状态不同时,轮轨噪声与车内噪声有明显差异;2．当车轮多边形幅值相同时,高阶多边形可以引起更高的轮轨噪声和车内噪声;3．改变车轮多边形的相位,可以获得不同的车轮径跳值,但是对轮轨噪声和车内噪声几乎没有影响。     

汽车悬置系统隔振性能分析与优化设计

针对传统汽车悬置系统能量解耦率低,振动传递率高的问题,建立了悬置系统动力学分析模型。将汽车动力总成悬置系统的振动性能分析和参数测试与系统模态耦合和振动能量解耦匹配理论相结合,采用MATLAB软件编制的程序来计算系统能量分布,并在满足悬置系统设计约束的前提下对系统悬置刚度值与布置参数进行了优化。某型号汽车悬置系统优化设计与振动性能测试结果验证了优化方案的有效性和可行性。     

基于ETAS系统的车用氧传感器综合性能测试

为减少汽车尾气对环境造成的污染,通过对发动机空燃比的控制方式和控制要求的研究,制定了发动机在3个工况下空燃比的控制策略:稳态部分负荷工况,采用开环与闭环控制相结合,开环环节采用查MAP图的形式,确定基本喷油量,以EGO信号为反馈信号,实行空燃比闭环控制;瞬态工况,运用开环控制,采用进气管压力观察器理论和动态油膜补偿模型,精确计算进气量和对燃油的补偿;怠速工况,转速稳定性采用闭环控制,以转速为反馈信号,喷油控制采用空燃比闭环控制。在Matlab/Simulink环境中分别进行建模,最后通过搭建的试验台进行了测试实验。结果表明,被测氧传感器的测试性能与标准氧传感器的参考数据相同。     

车内噪声主动控制发展综述及其在实车上的应用

本文对小型轿车车内噪声分布及其声源进行了分析,对国内外研究者对噪声主动控制研究成果的发展历程作了综述,并介绍了噪声主动控制理论及模型,最后结合具体实车,介绍了目前应用在实车上的车内噪声主动控制范例.     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

The Reader Response Approach to Teaching of English Literature

During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context.